Apparatus for grinding screws



PATENT OEEICE.

HENRY A. ROWLAND, OF BALTIMORE, MARYLAND.

APPARATUS FOR GRiNDiNG sceiaws.

SPECIFICATION forming part of Letters Patent No. 272,4 80, dated February 20, 1883.

Application tiled December 15, 1882. (No modem To all whom 'it may concern Y .Be it known that I, HENRY A. RowLAND, of the city ot' Baltimore, in the county of Baltimore, State ot Maryland, have invented a new and useful Improved Apparatus for Grinding Screws. which improvement is fully set forth in the following specification and accompanying drawings, in which- Figure l is an external elevation of the improved nut. Fig. 2v is a section of said nut cut by a plane passing through the center and parallel with its axis. Fig. Sis a section of said nut cut by a plane passing through the center and at right angles to its axis.

My invention consists in a nut, made'as hereinafterA described, for the purpose of grinding a screw.

Great difficulty has been heretofore experienced by machinists in making a screw free from sensible error, and various means have been adopted for this purpose, but none ot' them have been altogether successful.v

My invention does not relate to the cutting of screws in the first place, but to the grinding and perfecting ot' them after they have been cut by any of the well-known methods.

1n the drawings, A and A are two sleeves, connected together by set-screws F F F, perforated at dil'erent points, and fitting closely l upon the ends of the double-taper cere B.

B is the main portion of the nut, a double-4 taper hollow core, made of brass or other suitable material, provided with a iiange, I, round the middle and divided into any number of segments, with a screw-thread cut on its interior.

C C are two rings, connected by screws E E E, Svc., and resting upon the flan ge I of the double-taper core.

J J J are Wedges introduced between the vsegments of the core B.

H H, Sto., are holes cut through the'sleeves A A, just over the spaces between the segments of the core B. v

It will be seen from the foregoing that when the screws E E, Sto., are loosened and the screws -F F, &c., tightened the segments of the core will be drawn together. When the bore has reached the desired size the wedges the screw-threads.

J J, Src., are introduced between the segments, midway of their length, thus checking the further action of the sleeves. It' then the screws E E are tightened, clamping the rings O C 'firmly upon the ange I, the `whole will become immovably iixed. If it should become necessary to decrease the size ofthe bore again, the screws E E,&c., and F F must .be loosen-cd andthe wedges partially withdrawn, when the above process may be repeated. lf, however, it is desired to enlarge thebore, this may be done by simply loosening the two sets of screws and driving the wedges farther in lietween the segments. These wedges may be substituted by any appliance that will produce the same result.

The screw to be ground is cut upon a rod, leaving the parts of therod adjacent to the ends of the screw of a less diameter than the screw, so as to allow the movement ot' the nut longitudinally upon the screw beyond its extremities. The-rod is then placed in a lathe, with a vessel of' water directly under it, so that the nut,when put on the screw, partially dips into the water, the object being to keep the whole at a uniform temperature. Any other ot' the well-known means of accomplishing this object may' be used. The weight of the nut may be counterbalanoed by cord, pulley, and weight, or other suitable means. A mixture of emery and oil is then Vintroduced through the holes H H, Sto. As the screw is revolved, irst in one direction and then in/the other, the nut, being kept from turning, will be caused to move back and forth over it bythe action of The nut is then removed and reversed, constantly tightening it as it wears. This operation is repeated with finer and finer emery until the screw is completed. The object of reversing the nut on the screw is to correct whatever periodic error may have occurred while the nut was in one positionthat is to say, the nut may grind the screwk while in one position and yet admit an error, which, occurring at the same poiift4 of each revolution, does not correct itself, whereas it' the nut be reversed the surfaces that formerly coincided and admitted the error will now be exactly opposite to one another. Where fore :Hindoe merly there wasaconcave and a convex surface that, coming together always at the same point, did not correct one another, I willnow have a convex and a convex surface coming together, the resultot which will be that each will destroy the other. I prefer that thc length of the nut be equal to the length of the screw to be ground.

I know thatnuts made of various materialssuch as lead, plaster, or brasshave been fon' inerly used for the purpose of grindingscrews,

and I do not claim the nutgenerally; vbutnthat which is new, and that ot' which I believe myself to be the first inventor, isa nut the vwear of which can be taken up by reducing the bore equally from all directions, and, secondly, eau at any moment be rigidlyiix'ed throughout its whole length, so as to have no possibility of relative movement of the parts.

Having thus described my inventioinwliatl claim as new, and desire to secure by Letters Patent, is f l. In an vamiaratus for grinding screws, the

double-taper core B, divided into segments,

and having a vscrew-thread vcut upon its inner walls. y y

2. In an apparatus for grinding screws, the double-taper corevB, divided into segments,

and having a screw-thread cut upon its interior, provided with means for reducing or increasing the size ofthe bore.

3. In an apparatus for grinding screws, the double-taper core B, provided with means for setting and maintaining said core in fixed posi tion.

et. In an apparatus for grinding screws, the f following elements: the perforated sleeve A A, connected by the screws F F F, passing; through the lugs D l) D, the doubletaper core B, provided with vthe flange I round itsl middle, cut with ascrew-thread on the interior, and

divided into any number of segments,the rines C (l, connected together by the vscrews E E,

&c.,and the wedges J J, &e., substantiallyr asy shown and described.

5. In an apparatus for grinding screws, the

following elements in combination: the sleeves 4 

